Key

Date
Name and Abbreviation
Event Type
Government Level
Government Map Color
Government Timelapse Map Color
How Affected
Law
Relationship
Successful?

Date

Many municipal incorporation compilations use Incorporation Date, generally based on the date of the incorporation law, court decree, proclamation, or local government enactment, in relation to events. In contrast, this resource uses Effective Date, which is based on when an event took effect under law. These dates often differ, sometimes by over a year. When statutes provided for a transition period where a government existed as a legal entity for certain purposes but its territory retained its previous government temporarily, the date when this transition period ceased is used. In some cases, the actual effective date may be ambiguous, particularly when based on a clerical action such as filing or recording a document in a particular office. When this occurs, the best possible date is used. For transparency, how an effective date is determined is shown when possible.

Under Event Year(s), this resource separately tracks the years between when a proposed change was initiated and when it either took effect or failed. When no effective date is entered, this year range is often used instead of the effective date. For sorting purposes, an exact sort date is assigned to each event, although the full sort date is only displayed in timelapses mapped in the Government pages.

With three exceptions, dates are recorded using the calendar in effect at the time of the event or source document. For areas under British control, dates before the effective date of the Calendar (New Style) Act 1750 will use the Julian Calendar and will reflect the beginning of the year as March 25. The following exceptions to this rule substitute the Proleptic Gregorian calendar:

  • Years in the Statistics pages.
  • Undisplayed sort dates.
  • Timelapses mapped in the Government pages, which use sort dates.

Name and Abbreviation

When possible, abbreviations used in this resource are modeled on the Indigo Book. The names and types of governments are never abbreviated, although articles (e.g., "The") and formulaic portions of the corporate style, such as the "Mayor and Council of," are omitted. In particular, words such as Mount and Saint are spelled out in government names even if primary source documents abbreviate them.

Some governments may have used different name spelling variants over time. If there is no evidence of a formal name change event and the variance in name spelling is minor, only the modern spelling is used.

Event Type

Term Description Only
Border
Changes?
Annexation The territory of a government is either only increased or only decreased, with all involved governments retaining their forms of government. yes
Any Type An artificial grouping of all event types.
Boundary Realignment The territory of governments is definitively established, perambulated, or is altered such that the territory of at least one government is both increased and decreased, with all involved governments retaining their forms of government. yes
Charter Amendment The charter of a government is amended. yes
Charter Amendment (Annexation-General) The charter of a government is amended with respect to the ability to alter its territory, without delimiting the tract involved. yes
Charter Amendment (Annexation-Specific) The charter of a government is amended with respect to the ability to alter its territory in a delimited tract. yes
Charter Amendment (Burgess) The charter of a government is amended with respect to the ability of its executive officer to preside over its legislative body.
Charter Amendment (Plat Recording) The charter of a government is amended to require or permit the adoption of an official plat or boundary description. yes
Charter Revival The charter of a government is validated or, if dormant, restored. yes
Charter Township An existing township is reorganized as a charter township.
City Classification An existing city is classified or reorganized as a different class of city.
Commission Form An existing municipality is reorganized under the commission form.
Conditional Annexation The territory of a government is increased for a limited time or under other agreed jurisdictional limitations, with all involved governments retaining their forms of government. yes
Conditional Reversion Territory attached for a limited time or under other agreed jurisdictional limitations to a government reverts to its former government, with all involved governments retaining their forms of government. yes
Council-Manager Form An existing municipality is reorganized under the council-manager form.
County Classification An existing county is classified or reorganized as a different class of county.
De Facto Merger A government ceases to exist or is wholly depopulated without having been formally dissolved, with or without its territory being attached to one or more existing governments. yes
Dissolution A government is dissolved, including by merger or consolidation, with or without its territory being attached to one or more existing governments. yes
Election Separation An existing government becomes independent from another government for election purposes.
First Class Township An existing township is reorganized as a first class township.
General Law An existing government is reorganized chiefly or entirely under the form and powers of government available to its type of government under general law.
Growth Area The territory of the unincorporated growth area of a government is altered, without altering the territory of the government itself.
Home Rule An existing municipality is reorganized under a home rule charter.
Home Rule (County) An existing county is reorganized under a home rule charter.
Judicial Organization An existing government becomes independent from another government for court purposes.
Legislative Body The size of a government's legislative body is increased or reduced.
Mayor-Council Form An existing municipality is reorganized under the mayor-council form.
Mayor-Council-Administrator Form An existing municipality is reorganized under the mayor-council-administrator form.
Municipal Classification An existing municipality is classified or reorganized as a different class of municipality.
Municipal Manager Form An existing municipality is reorganized under the municipal manager form.
New Borough A new government is created or an existing government is reorganized as a borough, either in name or form of government. yes
New City A new government is created or an existing government is reorganized as a city, either in name or form of government. yes
New City District A new government is created or an existing government is reorganized as a city district, either in name or form of government, that is not subordinate to another municipal corporation. yes
New Commission A new government is created or an existing government is reorganized as a commission, either in name or form of government. yes
New County A new government is created or an existing government is reorganized as a county, either in name or form of government. yes
New Department A new government is created or an existing government is reorganized as a department, either in name or form of government. yes
New District A new government is created or an existing government is reorganized as a district, either in name or form of government, that is not immediately below the national government. yes
New Federal District A new government is created or an existing government is reorganized as a district, either in name or form of government, that is immediately below the national government. yes
New Hamlet A new government is created or an existing government is reorganized as a hamlet, either in name or form of government. yes
New Hundred A new government is created or an existing government is reorganized as a hundred, either in name or form of government. yes
New Metro Township A new government is created or an existing government is reorganized as a metro township, either in name or form of government. yes
New Municipality A new government is created or an existing government is reorganized as a municipality, either in name or form of government. yes
New Name The name of an existing government is changed without changing the form or named type of government. yes
New Plantation A new government is created or an existing government is reorganized as a plantation, either in name or form of government. yes
New Precinct A new government is created or an existing government is reorganized as a precinct, either in name or form of government. yes
New Proto-Municipality A new quasi-municipal entity with limited powers is created, which remains dependent on another political subdivision.
New Province A new government is created or an existing government is reorganized as a province, either in name or form of government. yes
New Region A new government is created or an existing government is reorganized as a region, either in name or form of government. yes
New Road District A new government is created or an existing government is reorganized as a road district, either in name or form of government, that is not subordinate to another municipal corporation. yes
New School District A new school district is created.
New State A new government is created or an existing government is reorganized as a state, either in name or form of government. yes
New Territory A new government is created or an existing government is reorganized as a territory, either in name or form of government. yes
New Town A new government is created or an existing government is reorganized as a town, either in name or form of government. yes
New Township A new government is created or an existing government is reorganized as a township, either in name or form of government. yes
New Unincorporated Service District A new government is created or an existing government is reorganized as an unincorporated service district, either in name or form of government. yes
New Village A new government is created or an existing government is reorganized as a village, either in name or form of government. yes
Only Border Changes An artificial grouping of those event types with "yes" under the "Only Border Changes?" column.
Optional Form (County) An existing county is reorganized under an optional form of government.
Plat Recording A government adopts an official plat or boundary description without changing the form of government. yes
School District Annexation The territory of a school district is increased, with all involved school districts retaining their forms of government.
School District Classification An existing school district is classified or reorganized as a different class of school district.
School District Merger A school district is dissolved, with or without its territory being attached to one or more existing school districts.
School District Reversion Territory reverts to its former school district, with all involved school districts retaining their forms of government.
School Districts One or more school districts are created, altered, or dissolved.
Second Class Township An existing township is reorganized as a second class township.
Selectman-Administrator Form An existing municipality is reorganized under the selectman-administrator form.
Selectman-Manager Form An existing municipality is reorganized under the selectman-manager form.
Separation An existing government becomes independent from another government. yes
Separation (County) An existing county becomes independent from another county. yes
Small Municipality Form An existing municipality is reorganized under the small municipality form.
Special Charter An existing government is reorganized under a special charter granted by a sovereign.
State Land Cession Title is extinguished by or in favor of another sovereign state.
Subordination An existing government becomes dependent on another government. yes
Suburban Town An existing town is reorganized as a suburban town.
Township Classification An existing township is classified or reorganized as a different class of township.
Tribal Land Cession Indigenous title is extinguished by or in favor of another sovereign state.
Unincorporated Place Name The name of an unincorporated place is changed.
Voting Rights Act Conditional Inclusion Limited preclearance requirements by court order under Section 3 of the Voting Rights Act of 1965 are commenced for a government.
Voting Rights Act Preclearance Exclusion Preclearance requirements under Sections 3 or 5 of the Voting Rights Act of 1965 are ended for a government.
Voting Rights Act Preclearance Inclusion Preclearance requirements under Section 5 of the Voting Rights Act of 1965 are commenced for a government.

Government Level

Term Description
County Governments classified as counties or county equivalents by the U.S. Census Bureau, or OpenStreetMap administrative boundary levels 5 and 6.
Municipality Governments classified as minor civil divisions or incorporated places by the U.S. Census Bureau, or OpenStreetMap administrative boundary levels greater than 6. In general, the definition of Municipality in this resource is more broad than that used by many jurisdictions, which may limit the term to incorporated places only.
State Governments classified as states or state equivalents by the U.S. Census Bureau, or OpenStreetMap administrative boundary levels 3 and 4.

Government Map Color

Term Description
Blue Area is currently located within government, but no successful event has been associated with it.
Green Area has never been located within government, but an event has been associated with it.
Orange Area was formerly located within government, and a successful event has been associated with it.
Purple Area is currently located within government, and a successful event has been associated with it.
Red Area is selected and additional information concerning the area is available in the upper right-hand corner of the map.

Government Timelapse Map Color

Term Description
Blue Area is located within government on the event sort date, but is unaffected by any events on that date.
Orange Area is being removed from the government on the event sort date.
Purple Area is being added to the government on the event sort date.

How Affected

Term Description
Ascertainment The boundary of the government is definitively established based on monuments or its original location of record.
Consolidation The government, in conjunction with other governments, ceases to exist.
Creation A new government is formed.
Dissolution The government ceases to exist.
Division The government is divided into multiple new governments, with none retaining the same name as the divided government.
Expansion The territory of the government is increased.
Internal The government is affected in an uncertain manner without altering its boundaries or its name.
New Name The government starts being referenced by a particular name, including forms of government included in the name.
Old Name The government ceases being referenced by a particular name, including forms of government included in the name.
Overlap Only a portion of the government is affected, without altering its boundaries or name, but affects the entirety of that portion that overlaps the next highest level of government.
Part Only a portion of the government is affected, without altering its boundaries or name.
Reduction The territory of the government is decreased.
*Reduction The territory of the government is decreased, but affects the entirety of that portion that overlaps the next highest level of government.
Reference The government is not directly affected at the time of the event, but is noted to facilitate information retrieval.
Remainder The entirety of that portion of the territory of the government remaining after a simultaneous boundary alteration is affected.
Separation The government becomes independent of another government, or elevates to another level of government.
Subordination The government becomes dependent on another government, or drops to another level of government.
Swap The boundary of the government is affected in an uncertain manner.
Unknown Additional information is required to determine how the government is affected.
Whole The entirety of the government is affected, without altering its boundaries or name.

Law

Citations are modeled on the format used by the Legislative Reference Bureau of Pennsylvania to cite session laws (e.g., see 101 Pa. Code § 25.52), with deviations noted below.

Type Session Source Number Section
Act of January 2, 1934 (1st Sp.Sess., 56 Ex. Laws 78, No. 90, January 15, 1934) , § 10 [11-120]
Date Volume Page Published Context

Term Description
Context This part deviates from the model by using square brackets instead of parentheses. If used, this generally contains either a code section or a number to distinguish unnumbered items within a document section (e.g., [3] may reference the third law listed in a repealer section).
Date For most documents, the date the law was approved by the executive officer or a veto was overridden by the legislative body is used. An effective date or filing date may be used if no other date is known or readily available.
Number If the jurisdiction uses the word Chapter instead of Number to designate a document, the abbreviation Ch. is used. Additionally, when there are overlapping document numbers within a volume for categories of documents within the same broad document type (e.g., general versus local acts), additional information may precede the number to identify the nature of the document. When there is no document number or when it is not known, a placeholder ___ is used in its place.
Page When there is no page number or when it is not known (particularly in jurisdictions using electronic documents), a placeholder ___ is used in its place.
Published This part deviates from the model, and is only included when the source is a gazette with dated issues (e.g., Federal Register, Pennsylvania Bulletin).
Section When a document distinguishes between document sections and code sections, document sections are used in this part.
Session This part is only used when necessary to distinguish a special session from a regular session.
Source This part deviates from the model in that it generally uses the abbreviation found in the Indigo Book instead of jurisdiction-specific abbreviations that often repeat between jurisdictions. If a particular volume uses overlapping page numbers, additional information may follow to identify in which section of a volume the document is located.
Type Gazettes and session laws often contain documents other than acts, such as joint resolutions, constitutional amendments, legal notices, and other types of appendices. The actual document type is included in this part.
Volume In jurisdictions where the volume reference is the session year, this part is generally omitted unless the year does not match the date. In some jurisdictions, a volume may span over several physical books that may contain sub-volume numbers. These are generally not included if the pagination does not restart in each sub-volume.

Relationship

Term Description
direct The instrument or action directly implements or is inherent to the event.
enabling The instrument or action creates a procedure to allow a specific event to take place that is not generally applicable.
include The instrument or action is ancillary to the event, or is linked for informational purposes, and should be included in summary information sources.
indirect The instrument or action creates a general procedure to allow events to take place given a similar set of circumstances.
reference The instrument or action is ancillary to the event, or is linked for informational purposes.
reference* Should either be reference or include.
reinstated The law reinstates all or a portion of another law that was previously repealed.
repealer The law repeals all or a portion of another law.
unknown Additional information is required to determine the relationship between the event and the instrument or action.
validation The law provides a method to correct technical or procedural errors in event.

Successful?

Term Description
batch The event is derived from bulk data source that includes successful and unsuccessful actions.
misreported The event record is a placeholder for a misreported event, and does not describe an actual geohistory event.
no The event is completely verified to have been rejected.
no* The event is verified to have been rejected, but may require additional research.
no+ The event is derived from bulk data source that either includes only unsuccessful actions or includes a flag indicating the action was unsuccessful.
pending A final disposition has not yet occurred for the event.
placeholder The event record is a placeholder, and does not describe an actual geohistory event.
unknown Additional information is required to determine if the event was approved or rejected.
unknown~ The event is derived from bulk statistical data, and was reported as successful, but no corroborating evidence has been located to verify.
yes The event is verified to have been approved.
yes* The event is verified to have been approved, but may require additional research.
yes+ The event is derived from bulk data source that either includes only successful actions or includes a flag indicating the action was successful.
yes? The event possibly occurred based on cartographic evidence, but no authoritative source has been located to confirm.
yes^ The event is derived from bulk statistical data, and is believed to have been successful based on cartographic evidence, but no or insufficient corroborating evidence has been located to verify.
yes~ The event is derived from bulk statistical data that either includes only successful actions or includes a flag indicating the action was successful.